This invention relates to a method and apparatus for monitoring selection, production and quality of products, coproducts and byproducts converted from grain material preferably during wet milling.
The ability to monitor the processing of grain material is increasingly important in the grain milling and ethanol industries. Traditionally, mills accommodate various productions that often use similar processes and products. For example, some wet milling processes may be suited for ethanol or fructose production, and they can also be used for starch production. Today, the industry is focussing on integrating processes with product lines and increased product potential. Monitoring permits enhanced control of the distribution of products converted.
One preferred application of the present invention is monitoring the wet milling process used to separate corn into its four basic components: starch, germ, fiber and protein. There are five basic steps to this process. First the incoming corn is inspected and cleaned. Then it is steeped for 30 to 40 hours to begin breaking the starch and protein bonds. Next the product is coarsely ground to separate the germ from the rest of the kernel. The remaining slurry consisting of fiber, starch and protein is finely ground and screened to separate the fiber from the starch and protein. The starch is typically separated in hydrocyclone compounds. Then the starch can be converted to syrup or be fermented into other products.
The steeping equipment typically comprises a stainless steep tank which can hold about 3000 bushels of corn for 30 to 40 hours of soaking in 50 C water. During steeping, the kernels absorb water, increasing their moisture levels typically from 15% to 45%, and more than double their size. The addition of about 0.1% sulfur dioxide to the water prevents excessive bacterial growth in the warm environment. As the corn swells and softens, the mild acidity of the steepwater begins to loosen gluten bonds within the corn and to release starch. After steeping, the corn is coarsely ground to break the germ loose from other components. Steepwater is condensed to capture nutrients in the water for use in animal feeds and for use as a nutrient in later fermentation processes. The ground corn, in a water slurry, flows to a germ separator. Then, the process may comprise additional steps such as germ separation, fine grinding and screening, starch separation, syrup conversion and fermentation.
Although the chemical and biochemical reactions involved in corn wet-milling are still not fully understood, many engineering processes have been developed to facilitate wet-milling. One example is the counter-current steeping method described in Wet milling in Technology of Corn Wet-Milling and Associated Processes, 69-125, ed. P. H. Blanchard, London, England, Elesevier Sci. Pub, 1992. Several studies of the steeping process have been reported in the literature. See, for example, Steinke J. D. et al., xe2x80x9cSteeping maize in the presence of multiple enzymes,xe2x80x9d Cereal Chem., 68(1), 12-17, 1991; Yaptenco K. F. et al., xe2x80x9cA laboratory countercurrent steep battery for corn wet-milling,xe2x80x9d Cereal Chem., 73(2), 249-256, 1996 and Yang P. et al., xe2x80x9cA laboratory-scale continuous countercurrent steep system for corn wet-millingxe2x80x9d, Transactions of ASAE, 41(3), 721-726, 1998. All of the patents, articles and references set forth in this xe2x80x9cBackground of the Inventionxe2x80x9d are incorporated herein by reference.
The present invention is a method and apparatus for monitoring, preferably in real time, the physical or chemical conversion of a grain material. The method employs multivariate analysis of a sample from the converted product. In a preferred embodiment a steeping conversion is monitored by multicomponent chemical analysis of the steepwater.